using System;

public class Program

{

    public static void Main()

    {

        int n=int.Parse(Console.ReadLine());

        int rem,res=0;

        while(n!=0)

        {

            rem=n%10;

            if(rem>0)

            {

                res=res+rem;

            }

            n=n/10;

        }

        Console.WriteLine(res);

    }

}